The present invention relates to a cone tail chuck device or apparatus for chucking a work having a conical tail portion or conical tail portions, and a method for using the same apparatus.
An example of such a work capable of being chucked by the cone tail chuck apparatus of the present invention is an unprocessed semiconductor monocrystal ingot which is obtained in the Czochralski method. The conical ends of the monocrystal ingot are severed from the main body of the ingot in such a manner that the remaining body of the ingot assumes a shape like a right cylinder, which is necessary since the subsequent grinding process requires the monocrystal ingot to be held squarely and firmly at its ends by an external cylindrical grinding machine.
To obtain high precision in the grinding operation, it is necessary to cut away the conical ends of the ingot such that the resulting cutting planes are parallel with each other and roughly normal to the center line of the ingot, and such that the cut faces and edges are free from nicks, which are often made as a result that at the last stage of severance the weight of the conical end portion works as bending stress on the skinny connection and the connection is eventually broken without waiting to be clearly cut through. To prevent the breakage it is necessary to supportively hold the conical end portion as well as the main body of the ingot while the severing operation proceeds. However, since the conical end portions of the ingot is tapered, and change their shapes irregularly from ingot to ingot, and also since the tapering surfaces of the end portions are slippery by nature, it was usually very difficult to mechanically fasten the end portions. Thus, to cut off the end portions of the ingots with high precision and without creating of nicks was very difficult.